Test chambers having carefully controlled environments are in common use in laboratories engaged in biological research. These environments must be maintained at appropriate humidity levels to avoid adverse effects upon the specimen or specimens under consideration. Usually it is important to maintain a test chamber environment at a high relative humidity and preferably at least 90% relative humidity through a temperature range of about 30.degree. - 40.degree. C. Some environments require a relative humidity of at least 90% through a range of temperatures to 60.degree. C. The required humidity of the environment is provided and maintained by a humidifier.
Although the principles of humidifying air are well developed, heretofore laboratory humidifiers have included a type in which water has been heated in a chamber and gases have been bubbled through the water; no control was maintained over the water level or the temperature and thus no effective control was placed on the relative humidity being provided to the test chamber. In another type humidifier, the temperature, gas input and relative humidity of the humidifier are preset and not adjusted automatically to compensate for changes in the test chamber environment. Some humidifiers have operated at temperatures above the boiling point of water, such as that disclosed in U.S. Pat. No. 3,502,309.
This invention is a distinct improvement over those of the prior art in that it is a compact humidifier which provides the correct environment in a test chamber using automatic regulation of water level, quantity and temperature in the humidifier and maintains that environment at a substantially constant humidity responsive to control by the test chamber. Other features and advantages of the invention will be apparent from the following disclosure.